The present disclosure relates to a router using a non-volatile memory, for example, a spin torque-magnetic random access memory (ST-MRAM).
Along with a rapid spread of smart phones and tablet-type devices, an increase in network traffic is huge due to a delivery of large-volume contents including moving images. Meanwhile, a total power consumption of network equipment is also steeply increased. So, decreasing the power consumption is an urgent issue.
Among the network equipment, a router is considered to consume a lot of power. Specifically, a search engine for classifying packets is said to consume the most of the power in the router. An improvement in search processing becomes a key factor for decreasing the power consumption. In a packet classification process, the packets sent are classified using information including sender and receiver addresses and ports. Based on the classification, processing such as transfer to a specific destination, rejection and the like is performed. The classification is made by comparing and collating the information contained in the packets with the router set in advance in each processing.
For comparison and collation (or match retrieval), a device called as TCAM (Ternary Content Addressable Memory: associative memory) is often used. In the TCAM, data is compared in parallel in a round-robin system. It has an advantage of a high speed because all processing is done on hardware, but also has a disadvantage of an increase in the power consumption due to the parallel processing.
On the other hand, there is also a method of searching on software using a general memory by a tree search or a hash method. In this case, although the throughput is lower than that of the TCAM or the like for batch processing on the hardware, it is possible to significantly decrease the power consumption. The throughput can be improved by a method such as pipeline processing.
The processing made not by the device such as the TCAM but by an algorithm is expected for significantly lowering the power consumption of the search engine.
Along with a rapid development of various information apparatuses from mobile terminals to large capacity servers, further high performance improvements such as higher integration, increases in speed, and lower power consumption have been pursued in elements such as a memory element and a logic element configuring the apparatuses. Particularly, a semiconductor non-volatile memory has significantly progressed, and, as a large capacity file memory, a flash memory is spreading at such a rate that hard disk drives are replaced with the flash memory.
Meanwhile, the development of FeRAM (Ferroelectric Random Access Memory), MRAM (Magnetic Random Access Memory), PCRAM (Phase-Change Random Access Memory), or the like has progressed as a substitute for the current NOR flash memory, DRAM or the like in general use, in order to use them for code storage or as a working memory. A part of these is already in practical use.
Among them, the ST-MRAM performs the data storage using a magnetization direction of a magnetic material, so that high speed and nearly unlimited (1015 times or more) rewriting can be made, and therefore has already been used in fields such as industrial automation and an airplane.